DSP control method of single-phase inverters for UPS applications

This paper presents a new deadbeat control solution and a digital control strategy suited for high performance single-phase inverters capable to maintain very low THD of less than 1% in presence of unknown loads (linear or highly nonlinear). The method takes into account the digital model of the PWM inverter and derives a new set of gains for the voltage and current loops. The current loop gain obtained by this approach is shown to be higher than previously known and this leads to a better disturbance rejection and faster dynamic response. The control strategy was implemented on a 16-bit fixed-point DSP controller (ADMC401) and tested on a 5-KVA IGBT- based inverter switching at 20 Khz.